Lennert Boeckxstaens

We report a patient with stage IIA (cT2bN0M0) lung adenocarcinoma who developed new diffuse pleural, pulmonary, and nodal FDG uptake on ¹⁸ FDG-PET/CT after three cycles of neoadjuvant nivolumab plus cisplatin–pemetrexed, with slight regression of the primary tumour. These findings raised the diagnostic dilemma between disease progression and immune checkpoint inhibitor (ICI)-related sarcoid-like reaction (SLR). Rapid clinical and metabolic improvement after corticosteroid therapy supported SLR, which was subsequently confirmed histologically by noncaseating granulomas without viable tumour at surgery. This case highlights pleural involvement in SLR as a rare and diagnostically challenging immune-related adverse event.

Introduction: Idiopathic inflammatory myopathies are a heterogeneous group of disorders with overlapping clinical and imaging features. Advanced imaging such as 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) is increasingly used. The “tiger man” sign is a rare nuclear imaging sign associated with sarcoid myopathy and has been previously described in only two case reports of non-sarcoid myopathy. Eosinophilic fasciitis and myositis lie within a spectrum of eosinophil-associated disorders, for which evidence-based treatment remains limited. In this context, histopathological insights may offer significant diagnostic and therapeutic value. Case description: A 68-year-old male presented with pain and oedema of the lower legs and forearms, accompanied by recurrent nocturnal fever. He had a prior diagnosis of eosinophilic fasciitis two years earlier. Proximal muscle weakness of the upper legs was noted. Laboratory tests revealed systemic inflammation and elevated creatine kinase (CK) levels, suggestive of an inflammatory myopathy, while screening for infections and autoimmune serology was negative. 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) imaging demonstrated a “tiger man” sign, characterized by extensive patchy 18F-FDG uptake in the skeletal muscles of all four extremities. Histopathological analysis confirmed a T-cell-mediated, necrotizing eosinophilic myositis, with no evidence of sarcoidosis or malignancy. Treatment with tacrolimus and plasma exchange resulted in significant clinical improvement and regression of 18F-FDG PET abnormalities. Conclusion: This is the third report of the “tiger man” sign in a patient with a non-sarcoid myopathy, thereby expanding the differential diagnosis for this imaging finding. Whole-body imaging can identify hypermetabolic yet clinically silent muscular regions, thereby guiding a more accessible and relevant site for biopsy. Histopathological findings can enhance diagnostic certainty and guide a more effective treatment.

Cough is an underrecognized and atypical manifestation of giant cell arteritis (GCA), which may lead to diagnostic delay. Literature on cough in GCA is limited and lacks comprehensive data on clinical relevance. The aim of this study was to assess the frequency of cough at diagnosis in GCA patients and to compare clinical characteristics between those with and without cough. Consecutive patients diagnosed with GCA between 2000 and 2020 and followed for ≥ 12 months at the University Hospitals Leuven (Belgium) were included retrospectively. We included 398 GCA patients, of whom 72 (18%) reported cough. Patients with cough were slightly younger (69.8 vs 72.3 years, p = 0.019), more frequently had constitutional symptoms (94% vs 73%, p < 0.001), and less often had polymyalgia rheumatica (26% vs 50%, p < 0.001) or permanent visual loss (3% vs 19%, p < 0.001). They had higher C-reactive protein (86 vs 68 mg/L, p = 0.003) and erythrocyte sedimentation rate (80 vs 67 mm/h, p = 0.036), and lower haemoglobin (11.3 vs 11.8 g/dL, p = 0.008) and albumin (36.7 vs 38.4 g/L, p = 0.013). Positron emission tomography total vascular score (10 vs 5, p = 0.009) was higher in GCA patients with cough. Although time to first relapse was shorter (10 vs 13 months, p = 0.018), relapse probability [hazard ratio (HR) 1.15, 95% confidence interval (CI) 0.82-1.61, p = 0.420] and the probability of discontinuing glucocorticoids were similar (HR 1.10, 95% CI 0.80-1.50, p = 0.563). GCA patients with cough may represent a distinct phenotype associated with systemic inflammation and large-vessel involvement. Further prospective studies with standardized cough assessment are needed to clarify the role of cough in GCA.

Purpose This study aims to evaluate differences in PET/CT imaging of meningioma using both gallium-68- and fluorine-18-labelled somatostatin receptor (SSTR) tracers, to characterize incidentally detected meningiomas on SSTR PET/CT, and to analyse institutional experience with Peptide Receptor Radionuclide Therapy (PRRT) in meningioma. Methods This single centre retrospective study included all SSTR PET/CT scans of meningioma patients (2007-2024) performed with [⁶⁸Ga]Ga-DOTATOC, [⁶⁸Ga]Ga-DOTATATE or [¹⁸F]AlF-NOTA-octreotide. For lesions ≥ 1cm³, tumour uptake was quantified using three distinct delineation methods: an absolute SUV threshold of 2.3, a relative threshold of 1.73 × SUV_peak of a meningeal reference region, and a relative threshold of 11% of the lesion’s SUV_max. Tumour-to-background ratios were calculated. Meningioma patients treated with PRRT were identified from our institutional registry (2016-2024). Results Of 4,136 SSTR PET/CTs, 152 patients with 171 SSTR-expressing meningiomas were included. Incidental meningiomas were found in 3.7% of patients imaged for unrelated indications. Quantitative analysis of 86 lesions (≥ 1 cm³) showed robust uptake for [¹⁸F]AlF-NOTA-octreotide (n = 7), [⁶⁸Ga]Ga-DOTATATE (n = 73), and [⁶⁸Ga]Ga-DOTATOC (n = 6), without significant between-tracer differences across delineation strategies. All tracers demonstrated high tumour‐to‐meningeal uptake ratios with ratios ranging from 51 to 146 for [¹⁸F]AlF-NOTA-octreotide, 10-329 for [⁶⁸Ga]Ga-DOTATATE, and 12-76 for [⁶⁸Ga]Ga-DOTATOC, confirming excellent tumour-to-background contrast. Among 12 heavily pretreated patients receiving PRRT, disease control rate was 50%, median progression-free survival 8 months, and overall survival 20 months. Conclusion SSTR PET/CT enables high-contrast meningioma visualisation. [¹⁸F]AlF-NOTA-octreotide seems clinically interchangeable with gallium-68-labelled tracers, while offering logistical advantages. PRRT achieves meaningful disease stabilisation, supporting further validation in prospective randomised studies.

Previous studies have shown that patients with giant cell arteritis (GCA) who have vascular ¹⁸F-fluorodeoxyglucose (FDG) uptake at diagnosis are at increased risk for thoracic aortic complications. To measure the association between vascular FDG uptake at diagnosis and the change in aortic dimensions. Prospective cohort study. University Hospitals Leuven. 106 patients with GCA and FDG positron emission tomography (PET) imaging 3 days or less after initiation of glucocorticoids. Patients had PET and computed tomography (CT) imaging at diagnosis and CT imaging yearly for a maximum of 10 years. The PET scans were scored 0 to 3 in 7 vascular areas and summed to a total vascular score (TVS). The PET scan results were positive when FDG uptake was grade 2 or greater in any large vessel. The association between vascular FDG uptake and aortic dimensions was estimated by linear mixed-effects models with random intercept and slope. When compared with patients with a negative PET scan result, those with a positive scan result had a greater increase in the diameter of the ascending aorta (difference in 5-year progression, 1.58 mm [95% CI, 0.41 to 2.74 mm]), the diameter of the descending aorta (1.32 mm [CI, 0.38 to 2.26 mm]), and the volume of the thoracic aorta (20.5 cm³ [CI, 4.5 to 36.5 cm³]). These thoracic aortic dimensions were also positively associated with TVS. Patients with a positive PET scan result had a higher risk for thoracic aortic aneurysms (adjusted hazard ratio, 10.21 [CI, 1.25 to 83.3]). The lengthy inclusion and follow-up period resulted in missing data and the use of different PET machines. Higher TVS was associated with greater yearly increase in thoracic aortic dimensions. Performing PET imaging at diagnosis may help to estimate the risk for aortic aneurysm formation. None.

Background: Fluorine-18-labeled SSAs have the potential to become the next-generation tracer in SSTR-imaging in neuroendocrine tumor (NET) patients given their logistical advantages over the current gold standard gallium-68-labeled SSAs. In particular, [¹⁸F]AlF-OC has already shown excellent clinical performance. We demonstrated in our previous report from our prospective multicenter trial that [¹⁸F]AlF-OC PET/CT outperforms [⁶⁸Ga]Ga-DOTA-SSA, but histological confirmation was lacking due to ethical and practical reasons. In this second arm, we therefore aimed to provide evidence that the vast majority of [¹⁸F]AlF-OC PET lesions are in fact true NET lesions by analyzing their MR characteristics on simultaneously acquired MRI. We had a special interest in lesions solely detected by [¹⁸F]AlF-OC (“incremental lesions”). Methods: Ten patients with a histologically confirmed neuroendocrine tumor (NET) and a standard-of-care [⁶⁸Ga]Ga-DOTATATE PET/CT, performed within 3 months, were prospectively included. Patients underwent a whole-body PET/MRI (TOF, 3 T, GE Signa), 2 hours after IV injection of 4 MBq/kg [¹⁸F]AlF-OC. Positive PET lesions were evaluated for a corresponding lesion on MRI. The diagnostic performance of both PET tracers was evaluated by determining the detection ratio (DR) for each scan and the differential detection ratio (DDR) per patient. Results: In total, 195 unique lesions were detected: 167 with [⁶⁸Ga]Ga-DOTATATE and 193 with [¹⁸F]AlF-OC. The DR for [¹⁸F]AlF-OC was 99.1% versus 91.4% for [⁶⁸Ga]Ga-DOTATATE, significant for non-inferiority testing (p = 0.0001). Out of these 193 [¹⁸F]AlF-OC lesions, 96.2% were confirmed by MRI to be NET lesions. Thirty-three incremental lesions were identified by [¹⁸F]AlF-OC, of which 91% were confirmed by MRI and considered true positives. Conclusion: The DR of [¹⁸F]AlF-OC was numerically higher and non-inferior to the DR of [⁶⁸Ga]Ga-DOTATATE. [¹⁸F]AlF-OC lesions and especially incremental lesions were confirmed as true positives by MRI in more than 90% of lesions. Taken together, these data further validate [¹⁸F]AlF-OC as a new alternative for SSTR PET in clinical practice. Trial registration ClinicalTrials.gov: NCT04552847. Registered 17 September 2020, https://beta.clinicaltrials.gov/study/NCT04552847